ESTRO 2024 - Abstract Book

S3383

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Figure 2. The ratios M 0 /M B of the Farmer chamber (left) and PinPoint chamber (right) for three models: sensitive air volume, complete air volume, and complete air volume without chamber’s stem at E = 152 MeV.

Conclusion:

The ratios M 0 /M B of both cylindrical chambers investigated in this study exhibit dependence on both the magnetic field and the initial energy of the proton beam. The dependence of the smaller PinPoint chamber is shown to be larger than that of the Farmer chamber. Due to the constructional design of the chambers, the ratio depends on the polarity of the magnetic field and hence the direction of the Lorentz force with respect to the chamber’s axis. By scoring the deposited energy in the complete air volume as well as removing the chamber’s stem, the variation of M 0 /M B for both chambers decreases within the range of studied magnetic fields, where the dependence on the magnetic field polarity almost diminishes.

Keywords: MRgRT, Monte Carlo, GATE

3027

Proffered Paper

Beam monitoring and instantaneous dose-rate measurements with SiC detectors for FLASH radiotherapy

Giuliana Milluzzo 1 , Chinonso Okpuwe 1,2 , Marzio De Napoli 1 , Antonino Amato 3,4 , Fabio Di Martino 5,6,7 , Damiano Del Sarto 5,6 , Giuseppe Felici 8 , Luigi Masturzo 5,6,8 , Elisabetta Medina 9,10 , Jake Harold Pensavalle 5,6,8 , Anna Vignati 9,10 , Massimo Camarda 3 , Francesco Romano 1,11 1 INFN, Catania Division, Catania, Italy. 2 Università degli Studi di Catania, Physics & Astronomy, Catania, Italy. 3 STLab, Srl, Catania, Italy. 4 INFN, Laboratori Nazionali del Sud, Catania, Italy. 5 Centro Pisano per FLASH Radiotherapy, CPFR CISUP, Pisa, Italy. 6 Azienda Ospedaliero Universitaria Pisa, Fisica Sanitaria, Pisa, Italy. 7 INFN, Pisa Division, Pisa, Italy. 8 SIT-Sordina, Srl, Aprilia, Italy. 9 Università di Torino, Physics, Torino, Italy. 10 INFN, Torino Division, Torino, Italy. 11 Particle Therapy Research Center (PARTREC), University Medical Center Gro-ningen, University of Groningen, Department of Radiation Oncology, Groningen, Netherlands The recent discovery of the “FLASH” effect occurring delivering beams at average dose-rates exceeding 40 Gy/s and with a total irradiation time of < 200 ms, is leading to a growing interest in establishing the dosimetric and monitoring techniques that still assure the high accuracy needed for a future clinical transition of such beams. In particular, as most of the experimental evidences of the FLASH effect so far have been observed using pulsed low-energy ultra high dose rate (UHDR) electron beams, the accurate monitoring of the beam parameters during the irradiation clearly required in future clinical treatments with FLASH radiotherapy, implies the use of fast detectors able to both sustain the high dose delivered per single pulse (DPP) of UHDR electron beams and also measure the variation of the beam current during the single electron pulse lasting a few µs, without suffering of the saturation effects experienced with the standard ionization monitor chambers. Moreover, the accurate measurement of the possible variations in the Purpose/Objective: